Bird or bat detection and identification for wind turbine risk mitigation

ABSTRACT

An automated system for mitigating risk from a wind turbine includes a plurality of optical imaging sensors. A controller receives and analyzes images from the optical imaging sensors to automatically send a signal to curtail operation of the wind turbine to a predetermined risk mitigating level when the controller determines from images received from the optical imaging sensors that an airborne animal is at risk from the wind turbine.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/384,550 filed Dec. 20, 2016, which is a continuation of U.S. patentapplication Ser. No. 14/829,403 filed Aug. 18, 2015 and issued as U.S.Pat. No. 9,521,830, which claims the benefit of, and priority to U.S.Provisional Patent Application No. 62/040,081 filed on Aug. 21, 2014,all of which are herein incorporated by reference.

FIELD OF THE INVENTION

This disclosure relates generally to systems and methods for assessingand/or reducing the risk from wind turbines to birds and/or bats.

BACKGROUND

The spinning turbine blades of wind farms pose a risk to birds or batsthat fly through the volume swept by the turbine blades. Some governmententities may require wind farms to mitigate that risk, particularly forcertain bird or bat species protected by law or government regulations.For example, these government entities may require that mitigation ofthe risk to Golden Eagles or Bald Eagles from a proposed wind farm bedemonstrated before installation of the wind farm is permitted. Othergovernments may not require a permit, but may still issue penalties orfines for those wind farms that harm government identified birds orother animals.

Attempts to mitigate the risk posed by wind farms to protected bird orbat species typically involve curtailing (e.g., slowing or shuttingdown) operation of wind turbines when it is determined that protectedbirds or bats may be present. Existing mitigation methods typicallycannot specifically identify birds or bats that they detect, and maytherefore curtail operation of wind turbines more often than isnecessary to mitigate risk to protected bird and bat species. Thisresults in loss of energy and revenue. Further, existing mitigationmethods typically have a high capital cost.

SUMMARY

This specification discloses systems and methods that employ opticalimaging technology to mitigate the risk posed by wind turbines toairborne animals, and related systems and methods that employ opticalimaging to assess such risk prior to or after construction of a windfarm by surveying bird and/or bat populations in the vicinity of thewind farm site.

In one aspect of the invention, an automated system for mitigating riskfrom a wind turbine to airborne animals of a predetermined speciesincludes a plurality of optical imaging sensors and a controller. Thecontroller receives and analyzes images from the optical imaging sensorsto automatically send a signal to curtail operation of the wind turbineto a predetermined risk mitigating level when the controller determinesfrom images from the optical imaging sensors that an airborne animal ofthe predetermined species is at risk from the wind turbine. In somecases, the control subsequently sends a signal to resume normaloperation of the wind turbine when the controller determines fromadditional images from the optical imaging sensors that there is nolonger risk from the wind turbine to the airborne animal of thepredetermined species.

The controller may determine whether the airborne animal is a member ofa particular predetermined species before the airborne animal is closerto the wind turbine than the distance the particular predeterminedspecies can fly at a characteristic speed of the particularpredetermined species in the time required to curtail operation of thewind turbine to the predetermined risk mitigating level. Thecharacteristic speed of the particular predetermined species may be, forexample, the average horizontal flight speed of the predeterminedspecies or the maximum horizontal flight speed of the predeterminedspecies. In some examples, the signal may automatically cause at leastone of the windmills to initiate the curtailment operations. In otherexamples, the signal is sent to an operator or technician who makes thejudgment call to send a command to at least one of the windmills toexecute a curtailment operation.

In some variations the predetermined species include Golden Eagles. Insome of these variations the controller determines whether each airborneanimal it detects in images from the optical imaging sensors is a GoldenEagle before the detected airborne animal is closer than about 600meters to the wind turbine. The controller may detect at a distancegreater than about 800 meters each airborne animal that it subsequentlydetermines is a Golden Eagle.

In some variations the predetermined species include Bald Eagles. Insome of these variations the controller determines whether the airborneanimal is a Bald Eagle before the detected airborne animal is closerthan about 600 meters to the wind turbine. The controller may detect ata distance greater than about 800 meters each airborne animal that itsubsequently determines is a Bald Eagle.

The plurality of optical imaging sensors may be arranged with a combinedfield of view of about 360 degrees around the wind turbine. The opticalimaging sensors may be arranged with overlapping fields of view. In somevariations, at least some of the optical imaging sensors are attached toa tower supporting the wind turbine. In some variations one or more ofthe optical imaging sensors is arranged with a field of view directlyabove the wind turbine.

The system may include a deterrent system that deploys deterrents, suchas flashing lights or sounds for example, to deter the airborne animalsfrom approaching the wind turbine. In such variations, the controllermay automatically send a signal to the deterrent system to deploy thedeterrent if the controller determines that the airborne animal of thepredetermined species is approaching the wind turbine.

In another aspect, an automated system for mitigating risk from a windturbine to birds or bats of one or more predetermined species include aplurality of optical imaging sensors and a controller. The controllerautomatically receives and analyzes images from the optical imagingsensors and to automatically send a signal to the deterrent system todeploy a bird or bat deterrent if the controller determines from imagesfrom the optical imaging sensors that a bird or bat of the one or morepredetermined species is approaching the wind turbine.

The controller may determine whether each bird or bat it detects inimages from the optical imaging sensors is a member of a particularpredetermined species before the detected bird or bat is closer to thewind turbine than the distance the particular predetermined species canfly at a characteristic speed of the particular predetermined species inthe time required to curtail operation of the wind turbine to apredetermined risk mitigating level. The characteristic speed of theparticular predetermined species may be, for example, the averagehorizontal flight speed of the predetermined species or the maximumhorizontal flight speed of the predetermined species.

In some variations the predetermined species include Golden Eagles. Insome of these variations, the controller determines whether each bird orbat it detects in images from the optical imaging sensors is a GoldenEagle before the detected bird or bat is closer than about 600 meters tothe wind turbine. The controller may detect at a distance greater thanabout 800 meters each bird or bat that it subsequently determines is aGolden Eagle.

In some variations the predetermined species include Bald Eagles. Insome of these variations the controller determines whether each bird orbat it detects in images from the optical imaging sensors is a BaldEagle before the detected bird or bat is closer than about 600 meters tothe wind turbine. The controller may detect at a distance greater thanabout 800 meters each bird or bat that it subsequently determines is aBald Eagle.

The plurality of optical imaging sensors may be arranged with a combinedfield of view of about 360 degrees around the wind turbine. The opticalimaging sensors may be arranged with overlapping fields of view. In somevariations, at least some of the optical imaging sensors are attached toa tower supporting the wind turbine. In some variations one or more ofthe optical imaging sensors is arranged with a field of view directlyabove the wind turbine.

In another aspect, an automated system for surveying the population ofairborne animals of one or more particular species of interest includesa plurality of optical imaging sensors and a controller. The controllerautomatically receives and analyzes images from the optical imagingsensors and to automatically determine whether the airborne animalsdetected in images from the optical imaging sensors are members of theone or more particular species of interest. The particular species ofinterest may include, for example, Bald Eagles and/or Golden Eagles.

These and other embodiments, features and advantages of the presentinvention will become more apparent to those skilled in the art whentaken with reference to the following more detailed description of theinvention in conjunction with the accompanying drawings that are firstbriefly described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side perspective view of an example wind turbineillustrating a volume of space around the wind turbine defined byexample bird or bat risk mitigation methods and systems disclosedherein.

FIG. 2 is a top perspective view of an example of a wind turbine andbird or bat risk mitigation volume illustrated in FIG. 1.

FIG. 3 is a top perspective view of an example of a wind farmillustrating risk mitigation volumes defined by example bird or bat riskmitigation methods and systems disclosed herein, as well as thetrajectory of a bird flying through the wind farm and triggeringcurtailment for some wind turbines but not others.

FIG. 4 shows a view of an example of a wind turbine to which opticalimaging sensor modules are mounted according to example bird or bat riskmitigation methods and systems disclosed herein.

FIG. 5 shows a view of an example of a wind turbine to which opticalimaging sensor modules are mounted according to example bird or bat riskmitigation methods and systems disclosed herein.

FIG. 6 shows a view of an example of a wind turbine to which opticalimaging sensor modules are mounted according to example bird or bat riskmitigation methods and systems disclosed herein.

FIG. 7 shows an example block diagram of a system for mitigating riskfrom a wind turbine to birds or bats.

DETAILED DESCRIPTION

The following detailed description should be read with reference to thedrawings, in which identical reference numbers refer to like elementsthroughout the different figures. The drawings, which are notnecessarily to scale, depict selective embodiments and are not intendedto limit the scope of the invention. The detailed descriptionillustrates by way of example, not by way of limitation, the principlesof the invention. This description will clearly enable one skilled inthe art to make and use the invention, and describes severalembodiments, adaptations, variations, alternatives and uses of theinvention.

For the purposes of this disclosure, the term “airborne animal”generally refers to animals that employ aerial locomotion. This aeriallocomotion may be powered or unpowered. These airborne animals mayinclude flying and gliding animals such as birds, bats, insects, othertypes of mammals, other types of birds, or combinations thereof.

Referring to FIG. 1 (side view) and FIG. 2 (top view), thisspecification discloses automated systems and methods that employoptical imaging technology to detect airborne animals, such as birds orbats (e.g., bird 10) in flight near a wind turbine 100, determinewhether or not the detected bird or bat is of one or more particularprotected species requiring risk mitigation (e.g., a Golden Eagle or aBald Eagle), and based on that determination decide whether or not tocurtail operation of the wind turbine 100 and/or whether or not toemploy deterrent measures to deter the detected bird or bat fromapproaching the wind turbine 100. The systems and methods may, forexample, positively identify a detected bird or bat to be a member of aprotected species for which risk is to be mitigated, positively identifya detected bird or bat to be a member of a species for which risk neednot be mitigated, or determine that a detected bird or bat is not amember of a protected species for which risk is to be mitigated withoutidentifying the species of the bird or bat. In some cases, a protectedspecies is defined by a government in which jurisdiction the wind farmis located. But, in other examples, the system may include a list ofspecies that it classifies as a “protected species.” In other examples,the species that are considered to be a protected species may be basedon international treaties, non-governmental organizations, protectiongroups, industry experts, scientific studies, religious groups, otherindividuals, other organizations, or combinations thereof.

In these systems and methods the birds or bats may be first imaged at adistance from the wind turbine 100 greater than or equal to a distanceR, and the decisions to curtail or not to curtail operation of the windturbine 100 and to deploy or not to deploy deterrent measures may bemade before the bird or bat approaches closer than distance R to thewind turbine 100. The distance R is selected to provide sufficient timefor operation of the wind turbine 100 to be curtailed before thedetected bird or bat is likely to reach the volume swept by the windturbine blades 105, if the bird or bat is flying toward the wind turbine100 at a speed characteristic of a protected species for which risk isto be mitigated. A characteristic speed of a bird or bat species may be,for example, an average horizontal flight speed or a maximum horizontalflight speed.

Hence the distance R may be selected, for example, to be greater than orequal to the distance that a bird or bat of the protected species forwhich risk is to be mitigated can fly at that species' known averagehorizontal flight speed in the time interval required to curtailoperation of the wind turbine 100. Alternatively, the distance R may beselected for example to be greater than or equal to the distance that abird or bat of the protected species for which risk is to be mitigatedcan fly at that species' known maximum horizontal flight speed in thetime interval required to curtail operation of the wind turbine.

If the methods and systems are used to mitigate risk from the windturbine 100 for more than one protected species of bird and/or bat, Rmay be determined for example using a characteristic speed of thefastest of the protected species for which risk is to be mitigated.Alternatively, a separate distance R may be determined for eachprotected species for which risk is to be mitigated.

The distance R may be measured for example from near the base of thewind turbine tower 110 as shown in FIG. 1, from the wind turbine nacelle115, or from any other suitable location on the wind turbine or itssupport structure. R may conveniently be measured from at or near thelocation of one or more optical imaging sensors (further describedbelow) employed in the systems and methods, but this is not required. Inthe illustrated example, R defines the boundary of a substantiallyhemispherical mitigation volume 120 around the wind turbine 100.

Wind turbines with which the systems and methods of this disclosure maybe employed may have tower heights of, for example, about 60 meters toabout 120 meters and blade lengths of, for example, about 40 meters toabout 65 meters. Rotation of the blades 105 of such wind turbines 100may typically be reduced from a normal operating speed of, for example,about 6 to about 20 revolutions per minute (rpm) o about 1 rpm or less(e.g., to 0 rpm) in a time period (curtailment time) of, for example,less than about 20 seconds, or less than about 30 seconds. A rotationspeed of about 1 rpm or less for such wind turbines 100 may typically bedeemed by regulatory authorities to pose an acceptable risk togovernment-protected bird and bat species. Full curtailment to 0 rpm maybe preferable and obtainable in these time intervals. While the aboveexamples have been described with a specific type of windmill tower, anyappropriate type of windmill tower may be used in accordance with theprinciples described in the present disclosure. For example, the towerheight may exceed 120 meters and/or the blade length may exceed 65meters. Further, the normal operating speed of the wind turbines and thecurtailment speeds may be outside of the parameters described above.Also, the windmill's turbines may operate at the curtailment speeds forany appropriate amount of time.

As examples, Golden Eagles have an average horizontal flight speed ofabout 13.5 meters/second and Bald Eagles have an average horizontalflight speed of about 18.0 meters/second. Using these speeds, a value ofR equal to about 800 meters would provide about 44 seconds in which tocurtail the wind turbine 100 for a Bald Eagle and about 59 seconds inwhich to curtail the wind turbine 100 for a Golden Eagle. A value of Requal to about 600 meters would provide about 33 seconds in which tocurtail the wind turbine 100 for a Bald Eagle, and about 44 seconds inwhich to curtail the wind turbine 100 for a Golden Eagle. These valuesfor R thus likely provide sufficient time in which to curtail operationof a wind turbine 100 to about 1 rpm or less (e.g., to about 0 rpm), andhence are likely suitable for mitigating risk to Golden Eagles and BaldEagles using the systems and methods of the present disclosure.

Referring now to the schematic block diagram of FIG. 7, the bird and batrisk mitigation systems of the present disclosure may include one ormore optical sensors (e.g., digital cameras) 122 located on or near awind turbine 100, one or more bird and/or bat deterrent systems 124, oneor more meteorological instruments 126, and one or more controllers 123in communication with the wind turbine 100, the optical sensors 122,meteorological instruments 126, and the deterrent systems 124. Theoptical sensors 122 image birds and/or bats in flight near the windturbine 100 and provide the images to the controller 123. The controller123 may implement an algorithm that determines whether or not an imagedbird or bat is of one or more particular protected species requiringrisk mitigation and whether or not the imaged bird or bat is approachingthe wind turbine 100. If the controller 123 determines that an imagedbird or bat is of a protected species for which risk is to be mitigated,and determines that the imaged bird or bat is approaching the windturbine 100 or is likely to approach dangerously close to the windturbine 100, the controller 123 signals the wind turbine 100 to curtailoperation, or signals the deterrent system 124 to deploy deterrentmeasures to deter the bird or bat from further approaching the windturbine 100, or signals the wind turbine 100 to begin curtailing itsoperation and signals the deterrent system 124 to deploy deterrentmeasures.

For example, the controller 123 may determine that an imaged bird or batis of one or more protected species requiring risk mitigation and isapproaching the wind turbine 100. While the bird or bat is still at adistance greater than R (defined above), the controller 123 may signal adeterrent system 124 to deploy a deterrent measure in an attempt todeter the bird or bat from further approaching the wind turbine 100. Ifthe controller 123 determines from further images from the opticalsensors 122 that the bird or bat was successfully deterred from furtherapproaching the wind turbine 100, the controller 123 may then determinethat it is not necessary to curtail operation of the wind turbine 100.If the controller 123 determines instead that the deterrents were notsuccessful and that the bird or the bat continues to approach the windturbine 100, the controller 123 may signal the wind turbine 100 or awind farm operator to curtail operation. The controller 123 may, forexample, in addition control the deterrent system 124 to continue todeploy deterrent measures while the bird or bat is within a distance Rof the wind turbine 100. If operation of the wind turbine 100 iscurtailed, after the controller 123 determines from further images fromthe optical sensors 122 that the bird or bat has left the proximity ofthe wind turbine 100 and is no longer at risk, the controller 123 maysignal the wind turbine 100 to resume normal operation and signal thedeterrent system 124 to cease deploying deterrent measures. In someexamples, the signals may be sent directly to a windmill to initiateeither the deterrent operations or the curtailment operations. In otherexamples, the signals may be sent to an operator of the windmills wherethe signals provide information that can be used by the operator todecide whether to send commands to the windmill to initiate thedeterrent system or the curtailment system. In these examples, thesesignals may include details about whether a criterion for determent orcurtailment has been met. For example, the signal may include a messageexplaining a bird is within 600 meters of a particular turbine. In thatsituation, the operator may study the behavior of the bird through thecameras in the windfarm and decide whether to initiate the curtailmentor determent operations. In other examples, the signal may include amessage that includes a recommendation with the details about thecriterion. In this situations, the operator can still decide whether tosend commands to the turbine to execute the determent and/or curtailmentoperations. In one such example, the message may explain that a bird iswithin 600 meters of the turbine and is kiting-soaring with tis headdown in hunting mode, which meets the curtailment prescription. Inanother example, the signal may include a message that explains that abird is within 600 meters of the turbine and is unidirectionalflapping-gliding with its head up, which is interpreted to be in saferstatus and curtailment prescriptions are not met. In each of thesesituations, the operator may make the decision to take further action.But, in other examples, the signals may be sent directly to thewindmills of interest without a human making a decision.

The system just described may employ deterrent measures and may curtailoperation of a wind turbine to mitigate risk to a bird or bat of apredetermined protected species. Other variations of such systems may beconfigured only to employ deterrent measures as described above and notto curtail operation of the wind turbine. Yet other variations of suchsystems may be configured to curtail operation of a wind turbine asdescribed above, but not to employ deterrent measures.

Optical sensors 122 employed in these systems may include, for example,one or more wide angle field of view (WFOV) cameras mounted with fixedfields of view for object detection and two or more high resolutioncameras mounted to pan and tilt to be capable of tracking andidentifying a bird or bat as it approaches or passes near the windturbine 100. The WFOV cameras may be arranged so that their combinedfields of view provide 360 degrees of coverage in many directions aroundthe wind turbine 100. Thus, the combined fields may include a sphericalvision around the windfarm. The cameras may have the ability to move totilt upward, tilt downward, rotate, or otherwise move. One or moreadditional WFOV cameras may be arranged with their fields of viewpointed upward to provide, in combination with the other WFOV cameras,substantially hemispherical coverage as depicted in FIG. 1 in themitigation volume (e.g. 120). The tracking cameras may be arranged toenable tracking and identification of birds or bats in the combinedfield of view of the WFOV cameras.

The WFOV cameras may be configured to image birds or bats for which riskis to be mitigated at a distance greater than R (defined above), forexample at a distance between about 600 meters and about 1000 meters, toprovide at least a low resolution blob-like image of the bird or bat.The WFOV cameras may additionally recognize other flying objects andhave the capability of initially determining if the flying object is ananimal or a non-living object.

The panning high resolution cameras are typically configured to imagethe detected birds or bats at a distance greater than R (e.g., betweenabout 600 meters and about 1000 meters) with sufficiently highresolution to provide information on size, shape, color, flightcharacteristics, and/or other features by which it may be determinedwhether or not the imaged bird or bat is a member of a protected speciesfor which risk is to be mitigated. The panning high resolution camerasmay be arranged (e.g., in pairs) with overlapping fields of view toprovide stereoscopic imaging of the birds or bats from which thedistance to the bird or bat and its speed and direction of motion(velocity) may be determined. While these examples have been describedwith specific detection distances, any appropriate detection distancesmay be used in accordance with the principles described in thisdisclosure. For example, the WFOV oprtional imaging sensors, the highresolution cameras, or the low resolution cameras may be able to captureimages of the airborne objects at distances greater than a 1000 meters.In some examples, the high resolution camera can capture images ofairborne objects in distances between 1000 and 10000 meters.

Any suitable cameras or other optical imaging sensors 122 may beemployed for the WFOV optical imaging sensors and the panning opticalimaging sensors. In some cases, the optical imaging sensors may generateimages from visible light, but the optical imaging sensors mayadditionally and/or alternatively be configured to image birds or batsat infrared wavelengths to provide images at night.

In some variations, an optical sensor 122 includes one or more WFOVcameras arranged to provide general object or blob-like visual detectionand two or more high resolution cameras arranged to provide stereoscopicimaging from overlapping fields of view to track birds or bats flying inthe field of view of the WFOV cameras. Two or more such modules may bedeployed on or around a wind turbine to provide the 360 degree coveragedescribed above.

The meteorological instrumentation 126 may measure climate conditions topredict and/or identify the bird or bat or the behavior of the creature.The meteorological instruments 126 may include at least one of abarometer, ceilometer, humidity detector, rain and precipitation sensor,visibility sensor, wind sensor, temperature sensor, and the like.Specific environmental and climate conditions may determine animalbehavior. For example, wind speed and temperature conditions may affectbat feeding behavior. The meteorological instrumentation 126 may alsocollect seasonal information.

Any suitable controller 123 may be used to control bird and/or bat riskmitigation for the wind turbine. The controller 123 may include, forexample, a processor and associated memory and input/output ports orwireless receivers and transmitters that communicate with the windturbine 100, the optical sensors 122, the meteorological instruments126, and the deterrent system 124. The controller 123 may be implementedwith a programmable computer. The system may include a separatecontroller for each wind turbine. Alternatively, a single controller 123may control risk mitigation for two or more wind turbines. A controller123 may be located on a wind turbine or anywhere else suitable. Acontroller 123 may communicate with its associated optical sensors 122and wind turbine 100 (or wind turbines) wirelessly, or through opticalor electrical cable for example. The controller 123 may additionally tapinto a fiber system associated with the wind tower 110 and wind farm.

The controller 123 may implement an algorithm in which it receives fromthe WFOV camera or cameras images in which it detects a bird or bat at adistance greater than R from a wind turbine 100. The controller 123 thencontrols the one or more high-resolution tracking (e.g., pan/tilt)cameras to track the bird or bat and collect and analyze high resolutionimages from which the controller 123 determines the distance to the birdor bat, its speed and direction of travel, and its height above groundlevel. The controller 123 may also determine from the high resolutionimages whether or not the bird or bat is of a protected species forwhich risk is to be mitigated (e.g., whether or not it is a Golden Eagleor a Bald Eagle). The controller 123 may make the determination based oncolor, shape, size (e.g., wing span), flight characteristics (e.g.,speed, wing motion and/or wing beat frequency), and/or any othersuitable features of the bird or bat. If the bird or bat is a member ofa protected species for which risk is to be mitigated and is approachingdangerously close to the wind turbine 100 or likely to approachdangerously close to the wind turbine 100, the controller 123 signalsthe wind turbine 100 to curtail operation and/or signals a deterrentsystem 124 to deploy a deterrent measure as described above. Ifoperation of the wind turbine 100 is curtailed, after curtailing thewind turbine 100, the controller 123 may continue to track the bird orbat with one or more tracking high-resolution cameras through theoptical sensors 122 and collect and analyze images of the bird or batfrom the one or more WFOV cameras and the one or more trackinghigh-resolution cameras until the bird or bat is no longer at risk fromthe wind turbine 100. For example, until the bird or bat is sufficientlyfar from the wind turbine 100 (e.g., >R) and moving away from the windturbine 100. When the bird or bat is no longer at risk, the controller123 signals the wind turbine 100 to resume normal operation.

The controller 123 may additionally receive information from themeteorological instruments 126 to help determine the behavior of thebird or bat. The types of weather conditions collected by themeteorological instrumentation 126 may provide additional information tothe controller 123 to determine if the bird or bat undertakes avoidancemeasures. Wind speed and temperature conditions may be particular to batfeeding behavior. Seasonal information may be indicative of migratorybehavior. Other factors may also be indicative of migratory behaviorsuch as the nature of the airborne object's flight, flight patterns,other factors, or combinations thereof.

The controller 123 may use the additional information to make inferenceson the behavior of the bird or bat. For example, a hunting bird or batmay be at higher risk for collision with a wind tower 110. The huntingbehavior may cause the creature to not notice the wind tower 110 and maycreate an increased risk. The controller 123 may initiate curtailmentand deterrent system 124 sooner if a hunting behavior is detected.Alternatively, if the controller 123 determines the bird or bat is in amigratory or travel pattern, the controller 123 may delay curtailmentand deterrence. The migratory and/or traveling creature may be morelikely to notice the wind tower 110 and naturally avoid the structure.The behaviors of the bird may be classified to assist in determiningwhether the birds are demonstrating hunting behavior, migratorybehavior, other types of behavior, or combinations thereof. Examples ofbehavior categories may include perching, soaring, flapping, flushed,circle soaring, hovering, diving, gliding, unidirectionalflapping-gliding, kiting-hovering, stooping or diving at prey, stoopingor diving in an agonistic context with other eagles or other birdspecies, undulating/territorial flight, another type of behavior, orcombinations thereof. Behavior and activity prevalent duringpredetermined intervals (e.g. one minute intervals) can recorded as partof an information gathering protocol. As the bird's behavior is followedover a predetermined amount of time, the bird's behavior type can bepredicted.

Deterrent system 124 may deploy bird and/or bat deterrents. In someexamples, the deterrents include flashing lights and/or sounds.

In one variation of the systems and methods just described, the WFOVcameras may detect and image birds that may be Golden Eagles or BaldEagles at a distance of about 1000 meters or more from the wind turbine100. After or upon detection of the bird with the WFOV cameras, one ormore tracking high resolution cameras may begin tracking the bird at adistance of about 800 meters or more from the wind turbine 100. Based onthe images from the WFOV and tracking cameras, the controller 123determines whether or not to curtail operation of the wind turbine 100and/or whether or not to deploy deterrent measures, and accordinglysignals the wind turbine 100 and/or the deterrent system 124 before thebird is closer than about 600 meters to the wind turbine 100.

With the systems and methods of the present disclosure, wind turbines ina wind farm may be individually curtailed and then returned to normaloperation as a protected bird or bat for which risk is to be mitigatedpasses into and out of the individual wind turbine mitigation volumes.For example, the wind farm 128 depicted in FIG. 3 includes wind turbines100 a-100 e, each having a corresponding mitigation volume 120 a-120 e.As bird 10 (for this example, a Golden Eagle) flies through the windfarm, the bird 10 may initially approach wind turbine 100 b. Before thebird 10 enters mitigation volume 120 b, the bird 10 is identified as aGolden Eagle and wind turbine 100 b is instructed to curtail operation.As or after the Golden Eagle exits volume 120 b toward wind turbine 100d, wind turbine 100 b is instructed to resume normal operation.Operation of wind turbine 100 d is then similarly curtailed, and thenrestored to normal after the risk to the Golden Eagle has passed.Operation of wind turbines 100 a, 100 c, and 100 e are not affected bypassage of the Golden Eagle.

The systems mounted on the wind tower 110 may require a source ofelectricity to function. For example, the deterrent system 124,controller 123, optical sensors 122, and meteorological instruments 126may all be mounted on the wind tower 110. The systems may requireelectricity to properly function. The electricity may be supplied in amultitude of ways. The systems may tap into the wind tower 110 itselfand draw electricity that is generated by the wind tower 110. Thesystems may be hardwired into an electrical grid which may provide acontinuous power source. The systems may additionally be solar powered.The wind tower 110 may be equipped with solar panels which may fuel thesystems or the solar panels may be mounted in a nearby location and maybe wired to the systems to provide power. Additionally and/oralternatively, the systems may be battery-powered. For example, thesystems may run on an independent power system such as a fuel cell orsimilar battery function. In another embodiment, the systems may draw aprimary source of electricity from one of the sources mentioned hereinand may draw back-up electricity from a battery. The battery may besupplied by solar panels, the wind tower, and the like and may storeexcess energy for the systems to use when a main source of power isinadequate or non-functioning. The battery may be located directly onthe wind tower 110 or may be located at a nearby location and wired tothe systems as appropriate. In yet other examples, the system may bepowered by a small wind generator, the grid, a fuel cell generator,another type of generator, batteries, another type of power source, orcombinations thereof.

Although in the example of FIG. 3 the diameters of the mitigationvolumes are shown as less than the spacing between wind turbines thisneed not be the case. The mitigation volumes of different wind turbinesin a wind farm may overlap.

Referring now to FIG. 4 and FIG. 5, some variations of the methods andsystems just described employ two or more optical imaging sensor modules125 attached to a wind turbine tower 110 at a height H above groundlevel. Height H may be, for example, about 5 meters to about 30 meters.In some examples, the height H is about 10 meters. The optical imagingsensor modules 125 are arranged around the wind turbine tower 110 toprovide a 360 degree field of view as measured in a horizontal planeperpendicular to the tower 110. The field of view may also include avertical component so that the airborne objects located higher or lowerthan the cameras are also detected by the camera. In these examples, thecameras may be located at different heights or have an ability to tiltupwards or downwards. (The arrows shown emanating from the opticalimaging sensor modules 125 schematically indicate a portion of theirfields of view parallel to the tower 110). The illustrated exampleemploys four such optical imaging sensor modules 125 arranged around thetower 110 with a spacing of about 90 degrees between modules. Any othersuitable number and spacing of such optical sensor modules 125 may alsobe used.

Each optical imaging sensor module 125 may include one WFOV camera andtwo tracking high resolution cameras arranged with overlapping fields ofview to provide stereoscopic imaging and to track birds or bats flyingin the field of view of the WFOV camera.

As shown in FIG. 4 and FIG. 6, an additional optical imaging sensormodule 130 may be located on top of the wind turbine 100 (e.g., attachedto the top of the nacelle 115) with cameras pointed generally upward toprovide visual coverage directly above the wind turbine 100. Opticalimaging sensor module 130 may be identical to optical imaging sensormodules 125. Alternatively, optical imaging sensor module 130 may differfrom modules 125, for example, the optical imagine sensor module 130 mayinclude additional WFOV cameras. Any other suitable arrangement ofoptical imaging sensor modules 125, 130 may also be used.

Additional automated systems and methods may employ optical imagingtechnology similarly as described above to conduct bird and/or batpopulation surveys prior to or after construction of a wind turbine orwind turbine farm. Such automated surveys may determine, for example,the populations or observations of the presence and movements ofparticular protected species of birds and/or bats (e.g., Bald Eaglesand/or Golden Eagles) in an area in which a wind farm is to beconstructed or has already been constructed. A decision as to whether ornot to construct a wind farm may be based or partially based on theresults of such an automated survey. Similarly, a decision as to whetheror not to install a risk mitigation system at a proposed or an existingwind farm, such as those described above for example, may be based orpartially based on such an automated survey. Such systems and methodsmay be employed for onshore and/or offshore wind sites.

Such an automated bird and/or bat surveying system may include, forexample, one or more WFOV cameras as described above, and two or moretracking high-resolution cameras arranged as described above to trackbirds or bats in the field of view of the one or more WFOV cameras. Forexample, the system may include one or more optical sensor modules 125as described above. The system may also comprise a controller, forexample similar to controller 123 described above, in communication withthe cameras. The controller may implement an algorithm in which itreceives from the WFOV camera or cameras images in which it detects abird or bat. The controller may then control the one or morehigh-resolution tracking (e.g., pan/tilt) cameras to track the bird orbat and collect and analyze high resolution images from which thecontroller determines whether or not the bird or bat is of a particularspecies of interest (e.g., a protected species for which risk is to bemitigated). The controller may make that determination based, forexample, on color, shape, size (e.g., wing span), flight characteristics(e.g., speed, wing motion and/or wing beat frequency), and/or any othersuitable features of the bird or bat. For example, the controller maydetermine whether or not a detected bird is a Golden Eagle or a BaldEagle. If the detected bird or bat is a member of the species ofinterest, the controller may for example record images of andinformation about the detected bird or bat on a hard drive or in othermemory medium, or transmit such images and/or information to anotherdevice for storage. The controller may for example count the number ofinstances in which birds or bats of the particular species of interestare detected.

This disclosure is illustrative and not limiting. Further modificationswill be apparent to one skilled in the art in light of this disclosureand are intended to fall within the scope of the appended claims.

1-20. (canceled)
 21. A method for mitigating risk of an airstrike to anairborne animal by a wind turbine, the method comprising the steps of:optically imaging an airborne animal with an optical imaging sensor;providing images from the optical imaging sensor to a controller;analyzing the optical images with the controller to determine if theairborne animal is a likely member of a predetermined species; andsending a first signal to curtail operation of the wind turbine to apredetermined risk mitigating level for the airborne animal that isdetermined by the controller to be a member of the predetermined speciesand is at risk from the wind turbine.
 22. The method of claim 21,further comprising the steps of: continuing to optically image theairborne animal with the optical imaging sensor; analyzing the opticalimages with the controller to determine if the airborne animal is at areduced level of risk from the wind turbine; and sending a second signalfrom the controller to the wind turbine to resume normal operation ofthe wind turbine for the airborne animal that is determined to be at thereduced level of risk from the wind turbine.
 23. The method of claim 21,wherein the controller determines if the airborne animal is a member ofthe predetermined species at a distance from the wind turbine that isgreater than a distance the predetermined species flies at acharacteristic speed in a time required to curtail operation of the windturbine to the predetermined risk mitigating level.
 24. The method ofclaim 23, wherein the characteristic speed is a maximum horizontalflight speed or an average horizontal flight speed of the predeterminedspecies.
 25. The method of claim 21, wherein the controller determinesif the airborne animal is a member of the predetermined species at adistance from the wind turbine that is greater than 600 m.
 26. Themethod of claim 21, wherein the predetermined species is selected fromthe group consisting of: a golden eagle; a bald eagle, and a goldeneagle and a bald eagle.
 27. The method of claim 21, wherein thepredetermined risk mitigating level comprises decreasing a rotationspeed of the wind turbine that is less than 1 rpm over a time periodthat is less than 30 seconds.
 28. The method of claim 21, wherein theoptical imaging sensors comprise a plurality of optical imaging sensorsarranged to provide a combined field of view that envelops the windturbine.
 29. The method of claim 21, wherein the optical imaging sensorcomprises a digital camera.
 30. The method of claim 21, wherein thecontroller determines whether the airborne animal is approaching thewind turbine.
 31. The method of claim 30, wherein the first signal tocurtail operation occurs for an airborne animal of the predeterminedspecies that is within 800 m of the wind turbine and is approaching thewind turbine.
 32. The method of claim 21, wherein the analyzing stepfurther comprises determining whether the airborne animal exhibitsanimal behavior of higher risk for an airstrike with the wind turbine.33. The method of claim 21, wherein the analyzing step to determine ifthe airborne animal is a member of a predetermined species comprisesanalyzing one or more of the airborne animal size, shape, color, orflight characteristic.
 34. The method of claim 33, wherein the analyzingstep is of optical images of the airborne animal that is greater than1000 m from the wind turbine and the first signal is sent before theairborne animal of the predetermined species is closer than 600 m to thewind turbine.
 35. The method of claim 21, wherein the optical imagingsensor images at an infrared wavelength to provide a low-light detectionof an airborne animal.
 36. The method of claim 35, wherein the airborneanimal is a bat.
 37. The method of claim 21, wherein the controllerdetermines if the airborne animal that is a member of the predeterminedspecies is in a hunting behavior, wherein the first signal is sentsooner for the predetermined species in the hunting behavior than thepredetermined species that is in a non-hunting behavior.
 38. The methodof claim 21, further comprising the steps of: monitoring one or moremeteorological conditions with a meteorological instrument; andproviding the controller with the one or more meteorological conditionsfor predicting and/or identifying a behavior of the airborne animal. 39.A method for mitigating risk of an airstrike to an airborne animal by awind turbine, the method comprising the steps of: optically imaging anairborne animal with an optical imaging sensor; providing images fromthe optical imaging sensor to a controller; analyzing the optical imageswith the controller to determine if the airborne animal is a likelymember of a predetermined species and approaching the wind turbine; andsending a signal to deploy a deterrent to the airborne animal if thecontroller determines the airborne animal is a member of thepredetermined species, is closer than 600 m to the wind turbine and isapproaching the wind turbine.
 40. An automated system for mitigatingrisk from a wind turbine, the automated system comprising: an opticalimaging sensor; and a controller that receives and analyzes images fromthe optical imaging sensor to send a first signal to curtail operationof the wind turbine to a predetermined risk mitigating level when thecontroller determines from the images received from the optical imagingsensor that an airborne animal of a predetermined species is at riskfrom the wind turbine.